Null Safety Features in Kotlin

The following article describes how null safety features in Kotlin help prevent runtime errors.

In fact, Kotlin has built-in null safety features that help prevent runtime errors caused by null references. Accordingly, in Kotlin, null safety is implemented through a type system. In general, the type system treats the two differently.

Basically, by default, all types in Kotlin are non-nullable. In other words, types cannot hold a null value. However, nullable types can be explicitly declared by appending a ? to the type name. For example, String is a non-nullable type, while String? is a nullable type.

When a variable is declared as nullable, the compiler enforces null safety checks to prevent null pointer exceptions at runtime. So, the compiler will generate errors or warnings if you try to call a method or property on a nullable variable without first checking if it is null.

Further, Kotlin provides several null safety operators and functions. Therefore, it makes it easy to handle nullable variables safely. For example, the safe call operator (?.). With this operator, you can call a method on a nullable variable without causing a null pointer exception. Similarly, you can access a property. Therefore, if the variable is null, the expression returns null instead of throwing an exception.

Similarly, Kotlin also provides the Elvis operator (?:), which allows you to provide a default value for a nullable variable if it is null. So, it helps prevent null pointer exceptions and improves the reliability of your code.

In brief, Kotlin’s null safety features help prevent runtime errors caused by null references. So, it enforces null safety checks at compile time. Also, it provides operators and functions to handle nullable variables safely. Hence, the code becomes more robust.

Further Reading